“Spokeswoman Catherine Sewell [……] accused both nationalist parties of ‘arrogance and cowardice’ for ignoring Catholic teaching on abortion and warned them ‘not to take the Catholic vote for granted’.

She said SDLP candidates will also be singled out for attention during next year’s election over the party’s stance on gay marriage, with voters targeted with leaflets and visits to homes.

‘This is a direct assault against Catholic teaching on the matter, which has left devout Catholic voters furious and embarrassed at the antics of political parties who rely on the Catholic vote to get themselves elected.’

She added: ‘When these people are standing before the gates of hell the party whip won’t be of much use to them then.’ ”